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In this in-vitro study, we designed a 3D printed composite of zinc oxide (ZnO) nanoparticles (NPs) with photocatalytic activities encapsulated within hydrogel (alginate) constructs, for antibacterial purposes applicable towards wound healing. We primarily sought to confirm the mechanical properties and cell compatibility of these ZnO NP infused scaffolds. The antibacterial property of the ZnO NPs was confirmed by hydroxyl radical generation using ultraviolet (U.V.) photocatalysis. Titanium dioxide (TiO ), a well-known antibacterial compound, was used as a positive control (1% w/v) for the ZnO NP-based alginate constructs and their antibacterial efficacies compared. Among the ZnO group, 3D printed gels containing 0.5% and 1% w/v of ZnO were analyzed and compared with manually casted samples via SEM, swelling evaluation, and rheological analysis. Envisioning an in-vivo application for the 3D printed ZnO NP-based alginates, we studied their antibacterial properties by bacterial broth testing, cytocompatibility via live/dead assay, and moisture retention capabilities utilizing a humidity sensor. 3D printed constructs revealed significantly greater pore sizes and enhanced structural stability compared to manually casted samples. For all samples, the addition of ZnO or TiO resulted in significantly stiffer gels in comparison with the alginate control. Bacterial resistance testing on indicated the addition of ZnO NPs to the gels decreased bacterial growth when compared to the alginate only gels. Cell viability of STO-fibroblasts was not adversely affected by the addition of ZnO NPs to the alginate gels. Furthermore, the addition of increasing doses of ZnO NPs to the alginate demonstrated increased humidity retention in gels. The customization of 3D printed alginates containing antibacterial ZnO NPs leads to an alternative that allows accessible mobility of molecular exchange required for improving chronic wound healing. This scaffold can provide a cost-effective and durable antibacterial treatment option.

Additive manufacturing platforms that rely on thermoplastic feedstock materials are now expected to fabricate components intended for deployment in a wide variety of environments, necessitating an understanding of the ability of a material to perform within a broad range of conditions. The work presented here explored the effect of submerging two polyester materials widely used in fused filament fabrication processes in five common liquid media: distilled water, apple cider vinegar, Mexican Coca-cola, 200 proof ethanol and distilled white vinegar for a seven day duration. Mechanical testing, dynamic mechanical analysis and characterization of the fracture surfaces via scanning electron microscopy were used to understand the effect of liquid media exposure. The effects of polymer degradation due to hygroscopic and hydrolytic mechanisms effects were documented. The need for specific procedures for the testing of the environmental effects on the degradation of additively manufactured polymeric components is also highlighted.

In this study, we designed, synthesized, and characterized ultrahigh purity single-walled carbon nanotube (SWCNT)-alginate hydrogel composites. Among the parameters of importance in the formation of an alginate-based hydrogel composite with single-walled carbon nanotubes, are their varying degrees of purity, their particulate agglomeration and their dose-dependent correlation to cell viability, all of which have an impact on the resultant composite’s efficiency and effectiveness towards cell-therapy. To promote their homogenous dispersion by preventing agglomeration of the SWCNT, three different surfactants-sodium dodecyl sulfate (SDS-anionic), cetyltrimethylammonium bromide (CTAB-cationic), and Pluronic F108 (nonionic)-were utilized. After mixing of the SWCNT-surfactant with alginate, the mixtures were cross-linked using divalent calcium ions and characterized using Raman spectroscopy. Rheometric analysis showed an increase in complex viscosity, loss, and storage moduli of the SWCNT composite gels in comparison with pure alginate gels. Scanning electron microscopy revealed the presence of a well-distributed porous structure, and all SWCNT-gel composites depicted enhanced electrical conductivity with respect to alginate gels. To characterize their biocompatibility, cardiomyocytes were cultured atop these SWCNT-gels. Results comprehensively implied that Pluronic F108 was most efficient in preventing agglomeration of the SWCNTs in the alginate matrix, leading to a stable scaffold formation without posing any toxicity to the cells.

Hydrogels are a class of biomaterials used for a wide range of biomedical applications, including as a three-dimensional (3D) scaffold for cell culture that mimics the extracellular matrix (ECM) of native tissues. To understand the role of the ECM in the modulation of cardiac cell function, alginate was used to fabricate crosslinked gels with stiffness values that resembled embryonic (2.66 ± 0.84 kPa), physiologic (8.98 ± 1.29 kPa) and fibrotic (18.27 ± 3.17 kPa) cardiac tissues. The average pore diameter and hydrogel swelling were seen to decrease with increasing substrate stiffness. Cardiomyocytes cultured within soft embryonic gels demonstrated enhanced cell spreading, elongation, and network formation, while a progressive increase in gel stiffness diminished these behaviors. Cell viability decreased with increasing hydrogel stiffness. Furthermore, cells in fibrotic gels showed enhanced protein expression of the characteristic cardiac stress biomarker, Troponin-I, while reduced protein expression of the cardiac gap junction protein, Connexin-43, in comparison to cells within embryonic gels. The results from this study demonstrate the role that 3D substrate stiffness has on cardiac tissue formation and its implications in the development of complex matrix remodeling-based conditions, such as myocardial fibrosis.

In this study, we designed, synthesized, and characterized ultrahigh purity single-walled carbon nanotube (SWCNT)-alginate hydrogel composites. Among the parameters of importance in the formation of an alginate-based hydrogel composite with single-walled carbon nanotubes, are their varying degrees of purity, their particulate agglomeration and their dose-dependent correlation to cell viability, all of which have an impact on the resultant composite’s efficiency and effectiveness towards biomedical applications. To promote their homogenous dispersion by preventing agglomeration of the SWCNT, at first, we used three different surfactants-sodium dodecyl sulfate (SDS-anionic), cetyltrimethylammonium bromide (CTAB-cationic), and Pluronic F108 (nonionic). After experimentation and corroboration through evidence obtained by characterization methods such as Dynamic Light Scattering, Rheology, Raman Spectroscopy, Conductivity, UV-Vis, Tensile testing and Swelling/Degradation studies with Dimensional Statistical Analysis, among others, it was determined that PF108 SWCNTs were the most stable for biomedical applications such as tissue engineering and biosensors.